Seattle’s mile-long downtown train tunnel. Nearly a century old, it’s so dangerous that firefighters and first responders could not enter in the event of an oil train fire.

“In all likelihood we would not send our first responders in,” Murray said.

Scoggins, taking particular note of the need for ventilation improvements, said: “It would be really challenging for a firefighter or anyone to go into that tunnel.”

Any fire would need to be fought from outside given ventilation and heat in the century-old structure.

About a dozen oil trains a week pass along the Seattle, Edmonds, Everett, Marysville and Bellingham waterfronts, carrying Bakken crude oil from North Dakota to four northern Puget Sound refineries.

The trains pass through downtown Spokane as they enter Washington, move south through Pasco, along the Columbia River to Vancouver, then north.

They are likely to grow in number, especially if Tesoro succeeds in building an oil-shipment terminal along the Columbia River in Vancouver.

In Seattle, 170,000 people live within half-a-mile of the railroad tracks. The Mariners and Seahawks’ stadiums sit just south of the tunnel entrance: Train whistles are a feature of televised Seattle sports events.

Sen. Maria Cantwell, D-Wash., and colleagues, have pressured the U.S. Department of Transportation to retire old, explosion-prone 1964-vintage tank cars, and to limit volatile components of crude oil (propane, butane, methane and ethane) in rail shipments.

“Current tank cars don’t have adequate protection,” Cantwell said Tuesday. “The railroads tell us they are building 40,000 cars a year. There are 37,000 (old) DOT-111 cars in use. We believe that (removal) can be accomplished by the end of the year.”

The senator noted that strict rules govern the amount of volatile components permitted in oil pipelines. No similar rules govern oil trains.

Describing herself as “very frustrated,” Cantwell said it is time to “rein in” volatile components on oil train cargoes. She wants the Pipeline and Hazardous Materials Safety Administration to issue an interim rule.

“People are putting volatility into a product that not even oil companies want,” said Cantwell.

“The longer we wait, the more we expose the public to the problems of these cars that aren’t especially robust,” the NTSB chairman said.

The Burlington Northern Santa Fe Railroad has issued regular updates, saying it is spending millions to upgrade tracks, and training hundreds of firefighters in emergency response. The BNSF brought tank cars to Interbay last year for training Seattle firefighters.

“If one of these events occurred, it would exhaust our resources and require assistance from communities around us,” Scoggins said.

The U.S. Department of Transportation promised last year that it would implement comprehensive safety rules. It has been repeatedly prodded by senators from both oil-producing and oil-refining states.

“This issue ultimately can be addressed only by the federal government,” Murray said.

Along with several colleagues, Cantwell has introduced the Crude-By-Rail Safety Act, which would immediately prohibit use of all DOT-111 tank cars and unjacketed CPC-1232 cars. It would force rules on volatile components.

The legislation requires railroads and shippers to disclose crude-by-rail movements to states’ emergency response coordinators. It would would institute a close-call reporting system in which employees can anonymously report safety problems.

Oil tanker cars derailed beneath the Magnolia Bridge in July of 2014. They were going only 5 miles an hour, but each carried 17,000 gallons of Bakken crude oil from North Dakota.

The Washington Fire Chiefs have asked the BNSF, Union Pacific and Canadian National Railroads to supply worst case scenarios and comprehensive emergency response plans. The BNSF has responded by offering to meet with emergency responders.

“I believe the threat is so significant in the heart of Seattle that I am not sure what is enough,” Scoggins said.

Asked if he has seen any comprehensive emergency response plan from the railroad, the chief added: “What I am saying is I haven’t seen it.”

The oil train issue has been burned into the national consciousness by a series of accidents in the last two years. Lac-Magnetic was the worst. A big explosion took place early last year outside New Casselton, N.D. A CSX train derailed and caught fire and forced evacuations in Lynchburg, Va.

In recent weeks, almost simultaneously, a CN train derailed and caught fire in Ontario, and a train caused a mushrooming fire along a riverbank in West Virginia. Luckily, neither accident took place in a population center.

Seattle saw a minor derailment of tank cars under the Magnolia Bridge last July. Each was carrying 17,000 gallons of Bakken Crude.